Toxic constituents of plants

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TOXIC CONSTITUENTS OF PLANTS:

TOXIC CONSTITUENTS OF PLANTS MUHAMMAD TANVEER KHAN M.PHIL. (PHARMACY)

WHAT ARE POISONOUS PLANTS?:

WHAT ARE POISONOUS PLANTS? While passing the life span, the plant not only produces food material but also certain other substances like alkaloids, glycosides, toxic proteins, bitter principles by its metabolic process. Most of these metabolic products/constituents are harmful to animal life. Plants containing such principles that have tendency of producing harmful effect are known as poisonous plants.

TOXIC PRINCIPLES OF POISONOUS PLANTS:

TOXIC PRINCIPLES OF POISONOUS PLANTS

1- Vegetable bases:

1- Vegetable bases They constitute vegetable nitrogenous bases as amines, purines and alkaloids. Amines are derived from amino acids and give poisonous characters to certain mushrooms. Purines help in producing active principles of certain tropical plants as tea and coffee. Alkaloids are complex heterocyclic nitrogenous bases and play an important role in many cases of poisoning e.g. morphine from poppy capsule, strychnine from Nux vomica .

2- Glycosides:

2- Glycosides These are the compounds that always split into a sugar part known as glycon and a non-sugar part known as aglycon. Cyanogenenetic glycoside is one of the important class that produce toxicity. These glycosides are harmless but give rise to toxic constituents under specific conditions e.g. amygdalin in bitter almonds.

3- Saponins:

3 - Saponins These are toxic to blood and are found in 400 species of 50 families. Saponins that cause toxicity are called as sapotoxins.

4- Bitter principles:

4- Bitter principles These possess a bitter taste with nauseatic and purgative action and are found in number of plants e.g. picrotoxin in Anamirata cocculus .

5- Toxic proteins:

5 - Toxic proteins These are also known as toxalbumins. These are mostly found in leguminosae and euphorbiaceae family. These toxalbumins have tendency of blood poisoning by agglutinating or precipitating RBCs. e.g. ricin in Ricinus communis .

6- Fixed oils :

6- Fixed oils These are the compounds of glycerol's with different kind of fatty acids. When heated, they are decomposed and give acrid acroelin vapours that are insoluble in water. They posses a purgative property and vesicant action on skin.

7- Essential oils:

7- Essential oils These are odorous principles of plants generally found in combination with glycosides. These are also volatile in nature. Large doses may cause GIT irritation, diarrhoea, vomiting and pain . They may also cause haemorrhage and abortion e.g. oil of juniper .

8- Organic acids:

8- Organic acids Organic acids like oxalic acid and formic acid are found in many plants that are irritants and produce toxicity.

FACTORS THAT DETERMINE THE TOXICITY OF PLANTS :

FACTORS THAT DETERMINE THE TOXICITY OF PLANTS There are many factors that determine whether plant ingredients are going to be toxic or not.

Correct identification:

Correct identification Proper identification of plants play an important role in the determination of toxicity. If there are several varieties of species then selection should be made very carefully in order to determine maximum amount of active ingredients.

Stages of growth:

Stages of growth The stages of plant growth are also an important factor in determining the toxicity. The green (unripen) berries of S olanum nigrum are toxic while the ripened ones are edible.

Condition of plant:

Condition of plant Certain plants e.g. potato which normally provide valuable food may acquire toxic properties during sprouting but loose their toxicity on drying and boiling.

Soil and cultivation:

Soil and cultivation Metabolic properties of plants are affected by; Structure of soil Moisture present in soil Temperature The difference in soil alters the production of poison.

Climatic conditions:

Climatic conditions M etabolic properties of plants are influenced by environmental conditions such as; Temperature Light Humidity For example, Alkaloid contents of some plants are less in rainy areas than in dry areas.

Toxic parts of plants:

Toxic parts of plants Different parts of plants vary in the amount of toxic ingredients. That’s why toxicity of root, stem, leaves, flowers and fruits vary considerable in the same stage of growth. One part of plant may be poison while other may not.

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